How do I start modding Spellbreak? Thread

Spellbreak is closing up shop, but the devs gave us a community version with source code, client, and server packages. I want to learn how to do mods for it. I started looking through the files, but I couldn't open the largest file. It is a .PAK file and it is around 22GB. I tried opening it in Notepad++ but I canceled it after a while because it seemed like it froze. Any tips on how to get started here?

Spellbreak Community Version: Sbcommunity.itch.io

It isn't possible to open the whole game in UE4 and make mods that way (I wish). There are ways to make mods though and some people are exploring the different options, but it's still early days.